It’s a story well-ingrained in our collective consciousness—the tale of the scientist
laboring long hours for months or even years in dogged pursuit of answers. It’s a
story we like to tell because it assures us someday our hard work will pay off. And
in Yoke Khin Yap’s case, it certainly has.

The professor of physics has pursued a research path that embodies this story of science,
taking an idea about certain nanomolecules from mere theory to, very soon, commercialized product. He also won the Bhakta Rath Research Award with student Chee Huei Lee in 2011. Yap’s contributions to fundamental understanding of boron-carbon-nitrogen nanostructures,
the development of transistors without semiconductors, and commercialization of high-brightness
fluorophores for medical imaging have been honored with his receipt of Michigan Tech’s
Research Award.

“Yap is one of the leaders in establishing application of boron nitride-based nanomaterials
for nanoscale devices,” Pandey says. “He has also led the efforts to encourage technology
development and commercialization activities at Michigan Tech.”

Lest Yap take too much pride in the award, however, Pandey adds that conducting research
isn’t the sole job of a professor: “Following the tradition of our department, he
is now looking forward to teaching a large introductory physics course after receiving
the Research Award.”

Stepping Stones

Somewhat mischievously, Yap credits some of his success to the quietude and space
for thinking deeply that a place like Michigan Tech affords away from the chatter
and noise of a large city. Though some may find the Houghton’s relative remoteness
unsettling, Yap says that for the past 15 years, on the banks of the Innovation Shore, he has been able to work quietly away at puzzling through big questions.

One of these big questions is whether transistors really need semi-conductors to function.
Answer: No, they don’t.

Transistors are core to the central processing units (CPU) of computers. They act
as either amplifiers or switches, either passing an electrical current through a circuit
board or controlling the flow of the current. There are millions of transistors in
CPUs, generally made with semiconducting silicon channels. Silicon, though a semiconductor,
does offer some resistance to the flow of electricity, which causes the channels to
heat up. The smaller the transistors, the worse the problem. This heat can literally
“fry” a CPU.

“Imagine you are driving a car from Hancock to Houghton,” Yap says by way metaphorical
explanation. “The lift bridge is the semi-conducting channel. You have resistance
in the form of traffic. If you don’t have the bridge, how will you go across the canal?
What if you make cars that can ‘jump’ a little bit, so they just need a stepping stone.
You can cross without a traffic jam.

“The way for an electron to do that is quantum tunneling. This quantum mechanics process
does not generate heat but allows electrons to cross. If an electron can tunnel across
without creating heat, it can bring the message across, and we can make a transistor
without causing heat, without causing a traffic jam.”

The solution is boron nitride nanotubes (BNNTs) coated with gold nanoparticles called quantum dots just one or two nanometers
apart. By applying a nominally higher potential energy, the electrons are able to
“tunnel” or “jump” between the nanoparticles. No semiconductor is needed to make such
tunneling transistor channels.

Somewhat paradoxically, BNNTs are electrically insulating, which led some in the physics
community to offer resistance. However, BNNTs can be used as a switch to stop electrons
from flowing on super-conductive materials like graphene, as demonstrated by Yap’s
follow-up work on graphene-BNNT switches. BNNTs are also superhydrophobic, transparent and anticorrosive, which means they
can potentially be used in difficult chemical and thermal conditions. Any scientist
conducting research in challenging environments knows the benefits such a breakthrough.

“A boron nitride nanotube is such a beautiful nanomolecule,” he says. “They are the
first nanomaterial designed by theory that was able to be realized. It is potentially
a breakthrough in physics, to theoretically design something and then make it.”

High-Brightness Fluorophores

Yap’s other line of research is also at the nanoscale, but otherwise bears little
likeness to BNNTs. High-brightness fluorophores are dyes that fluoresce in different
colors and degrees of brightness. They are used in machines called flow cytometers
to detect diseased cells in blood.

In 2014, Yap and his research laboratory team were accepted for the second time into
the National Science Foundation’s I-Corps team program, which trains scientists to
do market research. The I-Corps project allowed his team to identify the market of
flow cytometry and develop a viable business plan. In 2014, Yap established StabiLux Biosciences in partnership with Superior Innovations, a for-profit company founded with alumni
donations to nurture Michigan Tech innovations. Yap is currently on sabbatical at the University of Michigan in Ann Arbor, exploring
new collaboration on his work on high-brightness fluorophores.

Using fluorescent dyes can help medical personnel differentiate cells in the body.
Stabilux’s fluorophores offer enhanced signals to enable detection of cells that are
not detectable using current methods.

“We can use fluorophores to recognize biological substances, for example protein and
RNA,” Yap says. “Currently we are looking into antigen conjugations. This helps us
to understand the antigen profile on the surface of the cell, which helps us differentiate
what kind of cells we have. The fluorophore-tinted cells are so bright they allow
researchers to better analyze types of cells.”

Years in the making, Yap’s relentless pursuit of answers down multiple research paths
exemplifies his commitment to seeing a project through to its conclusions. More recently,
his work on nano-environment protection and 2-D materials beyond graphene have also started to gain attention.

Casually, Yap says: “I might have to spend another 15 years on this research.”

Michigan Technological University is a public research university, home to more than
7,000 students from 54 countries. Founded in 1885, the University offers more than
120 undergraduate and graduate degree programs in science and technology, engineering,
forestry, business and economics, health professions, humanities, mathematics, and
social sciences. Our campus in Michigan’s Upper Peninsula overlooks the Keweenaw Waterway
and is just a few miles from Lake Superior.

The Research Award

The Michigan Tech Research Award recognizes outstanding scholarly achievement by a
faculty member. It is based on the impact of the person's research, particularly sustained
research or a noteworthy breakthrough. The Michigan Tech Research Award is symbolic
of the university's high standard of research endeavors.

About the Author

Kelley Christensen

Kelley writes university research stories and articles for university publications.
She studied news-editorial journalism and American literature at the University of
Nebraska-Lincoln and holds a master's in technical communication from Montana Tech.
She is pursuing her doctorate in environmental policy at Michigan Tech.